BEIJING—GlaxoSmithKline PLC employees in China are said to have organized an all-expense-paid trip in May for a group of doctors to tour the scenic river town of Guilin, one of China's premier tourist destinations. The goal: Get Chinese doctors to begin prescribing the company's Botox medication, according to an anonymous tipster who alerted company executives.

Cui Lihua, a physician at Beijing's Bo'ai Hospital, was one of the more than 30 doctors invited on a three-day tour that included a trip to Elephant Trunk Hill...